Civil Engineering Reference
In-Depth Information
Since
0°, then
P
H
P
AE
18,500 lb/ft and
P
v
0.
Factor of safety for sliding:
FS
N
tan
P
p
33,600 tan 23°
740
___________
__________________
18,500
0.81
P
H
Factor of safety for overturning:
20
___
Overturning moment
18,500
3
123,300 ft
lb/ft
Moment of weight
235,200
FS
235,200
_______
123,300
1.91
Location of
N:
x
235,200
123,300
________________
33,600
3.33 ft
Middle third of the base of the wall:
x
4.67 to 9.33 ft. Therefore
N
is not within the mid-
dle third of the base of the wall.
10.9
Static analysis:
For the failure wedge,
W
1
2
(20) (11.1) (120)
13,300 lb/ft
R
12,000 lb/ft
FS
(
W
cos
R
sin
) (tan
)
________________________
W
sin
R
cos
(13,300 cos 61°
12,000 sin 61°) (tan 32°)
____________________________________
13,300 sin 61°
12,000 cos 61°
1.82
Earthquake analysis:
Using Eq. (9.2
a
) with
c
0 and including
R,
we find
(
W
cos
k
h
W
sin
R
sin
) (tan
)
__________________________________
FS
W
sin
R
cos
k
h
W
cos
where
k
h
W
0.20 (13,300)
2660 lb/ft
(13,300 cos 61°
2660 sin 61°
12,000 sin 61°) (tan 32°)
__________________________________________________
FS
13,300 sin 61°
12,000 cos 61°
2660 cos 61°
1.29
